Abundance and distribution of nanoplankton in the epipelagic subtropical/tropical open Atlantic Ocean

The objective of this research was to quantify the abundanceand distribution of nanoplanktonic particles available to frequentlyoccurring juvenile and adult planktonic copepods in the epipelagialof the open subtropical and tropical ocean. We chose locationsoff Puerto Rico and off the Bahamas to achieve our purpose.The hydrography for all stations revealed a thin upper mixedlayer, a thermocline with varying temperature decreases, salinitiesapproaching and surpassing 37     

Plio-Pleistocene sea level and temperature fluctuations in the northwestern Pacific promoted speciation in the globally-distributed flathead mullet Mugil cephalus

Background  

The study of speciation in the marine realm is challenging because of the apparent absence of physical barriers to dispersal, which are one of the main drivers of genetic diversity. Although phylogeographic studies using mitochondrial DNA (mtDNA) information often reveal significant genetic heterogeneity within marine species, the evolutionary significance of such diversity is difficult to interpret with these markers. In the northwestern (NW) Pacific, several studies have emphasised the potential importance of sea-level regression during the most recent glaciations as a driver of genetic diversity in marine species. These studies have failed, however, to determine whether the period of isolation was long enough for divergence to attain speciation. Among these marine species, the cosmopolitan estuarine-dependent fish Mugil cephalus represents an interesting case study. Several divergent allopatric mtDNA lineages have been described in this species worldwide, and three occur in sympatry in the NW Pacific.